Underfloor duct system and method of making



May 20, 1930. H. s. WALKER M 1,758,989

UNDERFLOOR DUCT SYSTEM ND METHOD OF MAKING Filed June 21, 1925 @9 Z f j@ZZ m Z G f4 E BY M7 Q O ATTORNEYS Patented May 20, 1930 HERVEY S.WALKER, F lA RDZMORE, PENNSYLVANIA UNDERELooR DUCT `sYsTEM AND METHOD'or MAKING Application filed June 21,

Thisinvention relates to systems of electrical Wiring and is concernedmore particularly with conduit or duct systems for instal. lation inbuildings during the course of construction thereof. The presentsystemAis ofv the concealed type with the ducts through which the conductorslare led placed eitherin thev fioors or in the Walls or partitions ofthe building, and the invention includes both a 1i. method of producinga novel duct system and also certain features of the system itself.

In modern buildings, especially oflice buildings, it has now becomenecessary to provide several different kinds of electrical lo service oneach floor of the building, as high tension energy is required forlighting and small power devices, such as fans, and in additiontelephone Wires and wiring for low tension signal systems, such asbuzzers, an-

2) nunciators, and the like, are also required.

The conductors for these different services are concealed in accordancewith present practice, and the conductors are led to the different partsof the floor in ducts which are built into the floor during the courseof construction of the latter. lSuch systems are commonly referred to asunderfloor Wiring systems.

In steel frame structures, such as modern office buildings, the floorsconsist of a rough fioor slab cast or built on suitable forms, thisslab' having a rough upper surface which is finished in severaldifferent Ways. When a Wood fioo'r is to be employed, sleepers are laidon the rough slab and the iinished Wood flooring is then laid on thesleepers. Another type of floor includes a finishinglayer of cementmortar which is laid over a fill of'V cinder concrete lying on the fioorslab, and over this finishing layer, linoleum or some other similarfinishing material is customarily employed. i

In the installation of a concealed wiring system in a floor of the typeabove generally described,'the ducts are placed in position during theconstruction of the floor and ordinarily laid in place on the roughfloor slab, being then covered bythe cinder fill and by thenishinglayer.v According to the pracy tice that has been used heretofore, theoutlets from the ducts are placed in positioniin the ducts at placesWherever it is known in L,advance that outlets will be needed, priortional to those originally installed are usually required. This is doneby cutting through the fioor, exposing the duct, placing an outlet inposition, and then patching the fioor around the outlet. This is anundesirable operation, involving much expense and inconvenience,particularly when carried on, as it usually is, when the floor space isin use.

The object of the present invention is to provide a system whichovercomes these diiiculties, and is readily flexible in -use to meetvarying requirements arising from. changes in points of energy demand onI,the floor. The system is further arranged so that changing theposition and number of outlet connections is a simple matter requiringno considerable mutilation of the floor covering or surface. T o attainthese objects, the system includes ducts provided with a large number ofoutlet fittings, or inserts at definite intervals along the ducts, thesefittings being placed in position prior to the completion of the floor,and supplied at a spacing such that there is a greater number offittings than would be required by the normal demand. These insertsextend upwardly from the duct which-lies beneath the fioor a substantialdistance, to the level of the finished floor surface or slightly beneathit, and the outlet ends of the inserts which are not to be used for thepassage of conductors are closed with caps which lie flush with thefinishing layer of the floor and are normallv concealed by the linoleum.The ducts conimunicate with boxes which form centers of distribution,and the boxes are provided with covers which are exposed in the floor.As the inserts in the ducts are at a uniform spacing, the location ofany insert may be readily ascertained by measurement from the box along'the ducts, and accordingly, although the inserts not in use are normallyconcealed, it is a simplematter to ascertain the posi- .of this type,long pads or bands of concrete at which current is desired, and a holemay then be cut in the linoleum, the insert opened i by removal of thecap, and connections to the conductors in the duct made in the usuallhile one form of the present wiring system frequently used includesducts or con duits in the form of metal tubes in which the fittings orinserts are mounted, I also contemplate that the ducts may be provldedby molding channels in the floor during its construction, and in theinstallation of a system will be placed on the rough ioor slab and thenchannels formed in these pads in any convenient manner, as, forexample,by placing a sleeper in the top of the band before the concrete has set.The open trench so formed may then be closed in any convenient manner,as, for` example, by means of a metal plate which is provided at uniformintervals with apertures in which'are placed the tubular insertsproviding the duct outlets. Such metal plates form the top wall of theduct, and the floor is then finished in the usual way, the metal platesbeing embedded in the ioor with the outlets extending through the latterto its upper surface. Preferably, the metal plate is strengthened bymaking it corrugated, although a suitable construction may also beprovided by using a flat plate and then forming narrow seams in the n.`ishing layer of the ioor at either edge bf the metal. With this latterconstruction, the seams in the finishing layer permit the upper surfaceof the floor to yield slightly in` the event that heavy loads are moved.across the duct, so that the cracking of the lfloor is prevented.

In another form of duct suitable for the purpose, a similar pad or bandof concrete is made, but the top of the channel formed in the band isclosed by an arched plate. This construction ,permits the use of arelatively shallow channel, the space in the duct being afforded in partby the dorning of the cover plate.

In any of the ducts above described, the outlets are placed at uniformspacing in accordance with the principles laid down in my co-pendingapplication, Ser. No. 63,355, filed Oct. 19. 1925. and which has maturedinto Patent #1,592,548 of which application the present one is acontinuation in part.

For a better understanding of the present invention, reference may behad to the accompanying drawings, in which- Fig. 1 is a transversevertical sectional view through one form of duct embodying the presentinvention,

Fig. 2 is a view similar to Fig. 1, showing a different type of duct,

ig. 3 is a view showing the manner in whic the duct shown in 1 isformed,

Fig. 4. is a view similar to Fig. 1, showing a different type-ofcoverplate,

Fig. 5 is a plan view of the cover plate used in the duct of Fig. 1,

Fig. 6 is a sectional view similar to Fig. 1, shfwmg a slightly modifiedtype of that duct, an

Fig. 7 is a diagrammatic lay-out' showing a system including the ductshown in Fig. 1.

Referring now to the drawings, the system is'shown4 in Fig. 1 installedin a iioor which consists of a rough floor slab 10, made of concrete inthe usual way. On the surface of thisslab is placed a la er of cinderiill 11, over which is placed the ishing floor layer 12 of cementmortar. As shown in Fig. 7 the system includes ducts 13 and 14 lying inthe fioor. and extending at right angles to each other, these ductsleading to boxes 15 throughrwhich the conductors in the ducts are led.The boxes have covers 16 which lie flush with the finished floorsurface, and upon removal of the covers access to the interior of theboxes is afforded. The arrangement of the ducts within the floor willvary with the particular installation,.but in anordinary building, ductswill be placed to run lengthwise and crosswise of the iioor atrelatively short intervals.

The ducts may consist of metal tubes of square or round cross-section,such as that illustrated at 17 in Fig. 2. These ducts are placed on thesurface of the floor slab 10 and connected to the boxes 15 prior to thelaying of the filling material. Each duct is provided with a pluralityof inserts 18 which are placed in the upper wall of the duct at uniform,relatively close spacing. For example, these inserts may be placed on 30centers, and the inserts not to be used are closed by caps 19. The ductis supported in any convenient way on the Hoor slab, preferably beingraised above the slab a 'short distance so as to be encased on all sidesby the cinder fill, and the height of the supports and the length of theinserts is such that the caps lie flush with the surface of thefinishing layer 12 or else a slight distance below. Such inserts as arerequired in nor mal use are opened by the removal of the caps andstandpipes of any preferred form are placed in the inserts, theconductors be ing drawn through the duct and led through the inserts inthe ordinary way.

By providing each duct with a plurality of inserts at relatively closespacing prior to the installation of the system'in the floor, it ispossible to secure outlets in such number that no matter what part ofthe floor requires service, there will always be an insert near at handand the use of this insert may be had without cutting the fioor andtapping the duct, as has been necessary in the previous systems. Whilesuch close spacing of the inserts will result in the presence in thefloor of a larger number of inserts than will ordinarily be required bynormal demand, still the inserts are of cheap metal construction 'andthe cost of the excessive quantity of inserts is not materially greaterthan the cost of the ordinary number of brass outlets which have beencommonly used for this purpose up to the present. Also, as thecaps ofthe inserts lie flush with the finishing layer of the fioor, or slightlybeneath it, they are normally covered by the linoleum so that theirpresence in the floor is not undesirable.

Instead of using a metal duct such as is illustrated in Fig. 2, it ispossible to employ a molded duct, as shown in Fig. l. In theconstruction of this duct, a pair of forms 20 is placed on the door,these forms` being of L-shape, and of any convenient material. Theheight of the upright legs of the forms and the spacing between theforms will depend on the needs of the particular installation- Betweenthe upright legs is placed a quantity of concrete 21, and while thismass is still plastic, one or more channels 22 may be molded in it, as,forexample, by means of a sleeper 23. When the concrete sets, thechannel 22 forms the major part of the duct, and this open channel maythen be closed lby a cover plate, as, for example, that shown at 2l inFig.'1. This cover plate is made of a sheet of metal, such as steel, andmay be strengthened by lengthwise corrugations. The plate is providedwith inserts 18 at uniform spacing, as shown in Fig. 5, and the duct isthus defined in part by the walls molded in the concrete band, and inpart by the metal plate. The height of the pad will depend on thethickness of the finishing layer of the fioor and the depth of thecinder fill, and the length of the inserts will be such that'when theplate is in position the tops of the inserts will lie flush with theupper surface of thefinishing layer, or slightly below it.

The strengthening of the metal plate by corrugations or in any otherconvenient many ner, is desirable in order to prevent the slightcollapse of the upper wall of the duct that might result if a heavy loadwere moved across theduct` but this difficulty may also be obviated bvusing the construction shown in Fig. 6. This includes a flat metal plate25 forming the upper wall of the duct 22 and having inserts 18atdefinite uniform and relatively close spacing. As is the case withv,the corrugated plate. the edges of the flat plate are provided withdownwardly extending flanges 26 which overlie the edges of the pad orband of concrete 21. lVhen this flat plate 25 is used. the finishingfioor layer is slotted as at 27. this permitting that part of thefinishing fioor layer 28 which overlies the duct to yield slightly asthe plate yields when loads are moved across the duct. y

In some instances it may be "desirable to make a duct in which thechannel 22 formed in the band of concrete is relatively shallow,additional space in the duct being secured by using a domed cover plate29. This cover plate has an upward bulge over the channel.

22, but is otherwise similar to the plates 25 and 24. v

vith any of the ducts employed in the present system, the insertscommunicating with the duct through 'its upper wall are embedded in thefloor itself, and are disposed at a relatively short spacing.` The ductthus lies embedded a substantial distance beneath the finished floorsurface, but outlets from. the duct are available in the floor surfaceshort distances apart. The molded ducts i1- lustrated in Figs. l, 4, and6 may be formed without difliculty during the construction of the floor,while the duct shown in Fig. 2 is prepared in advance and placed in thefloor at the appropriate time. With the molded duct, the cover plate maybe placed in position over the channel and the inserts then inserted init prior to completion of the floor, orl the inserts may be placed inthe plate before the latter is installed to cover the channel. Theoutlet fittings for use with the metal duct shown in Fig. 2, maylikewise be placed in position in t-he duct wall at the time of itsmanufacture 4or, else just before its installation.

I claim v 1. In a method of constructing a concealed y the plate withthe interior of the duct, and,

laying the upper layers of Hoor material on vthe said intermediate levelto enclose and conceal the duct and the outlet fittings, the top surfaceof the fioor lying substantially at the level of the tops of the outletfittings.

2. In a concealed wiring system for use in concrete buildings. a ductadapted to be disposed wholly within the floor structure at asubstantial distance beneath the finished floor surface, which comprisesthe combination of a band of fioor material laidon an intermediate levelof the floor and having an opentop channel formed in its upper surface,a metal plate covering the top of the channel and with it defining theduct, and a plurality of tubular inserts mounted `in the plate atselected intervals, these inserts havingoutlet endsv through whichaccess to the interior of the duct may be had through the finished fioorsurface.

3. In a concealed wiring system for use in concrete buildings, a ductadapted to be disposed wholly within the floor structure at asubstantial distance beneath the finished floorN surface, whichcomprises a band of floor ma v terial lying on an intermediate level ofthe floor and having an open-top channel formed in its upper surface, areinforcing plate lying on the top of theband and closing the channel,and a plurality of similar tubular inserts mounted in the platelengthwise of the channel at predetermined, uniform, relatively shortintervals, the plate and inserts being adapted to be enclosed andconcealed by the upper layers of the ioor with the inserts extending tothe upper level of the finishing floor layer and affording access to theinterior of the duct through their outlet openings.

4. In a method of constructing a concealed wiring system in the floor ofa building, the steps of laying a band of floor ma-y terial upon anintermediate level of the floor, forming a channel in the upper face ofthis band. closing the channel to complete the duct by a plate carryinga plurality of outlet fittings of similar height, and laying up` perlayers of floor material over the said intermediate level to enclose andconceal the duct and the said outlet fittings, the top surface of thefloor being laid to lie substantially flush with the level of the topsof said fittings.

5. In a method of constructin a concealed Wiring systemv in the floor ofa uilding, the steps of laying a band of floor material upon anintermediate level of the floor, forming a channel in the upper surfaceof this band mounting a plurality of outlet fittings of similar heightin a row and at selected intervals in a plate, closing the channel tocomplete the duct by placing the plate on the band, and laying upperlayers of floor material over the said intermediate level to enclose andconceal the duct and said fittings and to form a finished floor surfacesubstantially fiush with the level of the tops of said fittings. e

6. The method of constructing a door having a concealed wiring systemtherein, which comprises .forming a slab of floor material, placing aband of floor material on top of this slab, this bandhaving an openchannel in its upper surface, closing the channel by means of a platehaving a plurality of outlet fittings of similar height mounted therein,and placing a layer offilling material on theV slab and a finishinglayer over the filling material, the said layers being placed so thatthe upper surface of the finishing ylayer lies substantially flush withthe level of the tops `of the said fittings.

7. The method of constructin a floor having a concealed wiring system terein, which comprises placing outlet boxes on an'intermediate level ofthe cor, forming bands of floor material on the said intermediate levelbetween the boxes, vthis band having an open channel in its uppersurface ommunicatmg with the-interior of the boxes, closing the the topsof the boxes and fittings lying su l stantially at the level of theupper surface of the said finished floor.

8. The method` of constructing a floor hav- I ing a concealed Wiringsystem therein, which comprises formingaslab of fioor material, mountingoutlet boxeslfon this slab, forming a band of fioor materia'ontop ofthelslab between adjacent outlet boxes, this band being provided with anopen channel in its upper surface, closing the channel by means of aplate having a plurality of outlet fittings of similar height mountedtherein, and placing a layer of filling materialen the slab and afinishing layer over the filling material, the upper surface of thefinishing layer lying substantially flush with the level of the tops ofthe said fittings and the tops of the said outlet boxes.

9. The method of constructing a fioor having a concealed Wiring systemtherein, which comprises forming a slab of floor material, molding aband of floor material on the top of this slab, this band being formedwith an open channel in its upper surface, closing the channel by meansof a plate having a plurality of outlet fittings of similar heightmounted therein, and laying upper layers of floor material on thesaidintermediate level to enclose and conceal the duct formed by theband and the plate and also to partially conceal the said outletfittings, the top surface of the -fioor being laid to lie substantiallyflush with the level of the tops of the said fittings.

10. A ioor construction having a concealed wiring duct therein, whichcomprises a fioor slab, a band of floor material lying on the slab andhaving an open-top channel formed in its upper surface, a plate lying ontop of the band and closing the channel to form a top of the finishinglayer of the floor lying substantially flush with the tops of thefittings. 1

11. In a floor construction, the combination of a band of Hoor materiallaid on an intermediate level of the floor, this band 'having an openchannel in its upper surface, a metal plate having a; plurality of outllet fittings of similar height mounted therein placed on the band toclose `the channel and complete av wiring duct, upper layers of floormaterial laid on said intermediate level to-, complete the floor and toenclose the duct and the outlet Iittings,and narrow open channels formedin the upper surface of the Hoor lying parallel and lengthwise of theduct adjacent either' edge of the plate. Y

12. In a floor construction, the combination of a slab of floormaterial, a band of e, ioor material laid on the slab and having an openchannel in its upper surface, a plate closing the channel and having avplurality of outlet fittings of similar height mounted lo therein, alayer of filling material on the slab extending substantially to the topof the band, and a finishing layer over the filling material concealingthe plate, the outlet fittings projecting through the finishing layerand lying with their tops substantially level with the upper surfacethereof.

13. In a Hoor construction, the combina tion of a wiring duct Within thefloor structure below the floor surface, this duct being defined in partby a portion of the floor material having a channel therein and in partby a metal plate forming the top wall thereof, and a plurality of outletfittings of tubular form extending upwardly from the duct toward thefloor surface and held in place at least in part by the finishing layerof the ioor in which said fittings are embedded. f

In testimony whereof I aiiix my signature.

HERVEY S. WALKER. C

